In this pilot project, zebrafish will be exploited to develop a model system to study kidney development. We propose a candidate gene approach to examine genetic control of pronephros development. Previous studies showed that histological features of metanephric kidney development in mammals are similar to the simpler pronephros development in fishes. In addition, critical gene expression patterns and developmental genetic pathways that control metanephric kidney development are also found in zebrafish pronephros development, showing that zebrafish pronephros is a powerful tool that complements studies of metanephric kidney development in mammals. Morpholino antisense oligonucleotides analogs suppress translation of specific genes, and morpholino oligonucleotide (MO) injection into 1-16 cell stage zebrafish embryos effectively produces a knockout for protein expression (termed MO knockdown) throughout the entire embryo for up to 50 hours postfertilization (hpf). Zebrafish development is very rapid, and a functional pronephros is produced by 48 hpf. Therefore, MO knockdown will allow us to examine specific gene function during renal tubule development. Using this approach, we can develop a zebrafish reverse genetic model for kidney tubule morphogenesis and genetic kidney disorders (for example, polycystic kidney disease). In this proposal, experiments are outlined that will determine the structural and functional consequences of (a) inhibiting expression of cadherin cell adhesion molecules that are expressed during pronephros development, (b) inhibiting expression of molecules that result in cystic disease in mammals (for example, inversion and Tg737), and (c) inhibiting expression of proteins that are found in developing and differentiated podocytes (for example, podocalyxin).